1. FIELD OF THE INVENTION
The present invention relates to a novel process for preparing 2-naphthanoic acids, particularly substituted acids or esters thereof, by cyclizing a ketal or alpha-enol ether of an alpha-acetyl cinnamic acid or ester thereof.
2. DESCRIPTION OF THE BACKGROUND
Substituted 2-naphthanoic acids and esters thereof are useful as polymer intermediates in the chemical industry. However, the methodology for making these compounds is very sparse. The major problem posed by the synthesis of these compounds is that, for the 2-napthanoic acid derivatives to be useful as polymer intermediates, a second functional group besides the carboxyl group must be present. Moreover, such a functional group must be present as a specific location on the molecule. Thus, a single, specific isomer of a substituted 2-napthanoic acid or ester thereof must be produced out of a large number of distinguishable isomeric naphthanoic acids. The development of such a process is, therefore, of great significant to the industry.
Specific 2-naphthanoic acids have been synthesized by the prior art. For example, see U.S. Pat. Nos. 4,594,445; 4,506,092; and 4,486,605. However, none of these methods are applicable to the general class of 2-naphthanoic acids or esters synthesized by the process of this invention.
Accordingly, there is still a need for a simple and general process for the synthesis of 2-naphthanoic acids and esters thereof having a predictable substitution pattern.